1. Field of the Invention
The present invention relates to a standby system for controlling the operation of a film processor and related functions and more particularly to a standby control system which normally maintains the processor in a standby or idle condition but switches it to a full-on processing condition for a predetermined period of time when a film to be processed is detected in the processor infeed tray.
2. Description of the Prior Art
Standby control systems are known which control the operating mode of film processors by maintaining them normally in a standby mode and switching them to a processing mode only when film is detected in the processor infeed tray. Most of such prior standby systems, however, use mechanical detectors which physically touch the film in the infeed tray to detect its presence. However, such mechanical detectors are notoriously unreliable and require frequent adjustment.
A further disadvantage of some known standby control systems for film processors is that they often require extensive modification of the processor components such as infeed switches, signal pickup devices and infeed tray.
One known processor for processing lithographic film uses infrared light transmitted through the film to a receiver to detect the film's presence and thereby initiate a control function of the processor. The disadvantage of such a film detection means is that it requires that the standby system be built into the processor during its manufacture. Therefore it cannot be applied to existing processors. Furthermore, because of its built-in characteristics, such a standby control system lacks flexibility and versatility.
Accordingly, there is a need for a standby control system for film processors which does not rely on mechanical sensors for detecting the presence of film in the processor infeed tray, which is reliable in operation, which requires a minimum of adjustment, which can be embodied either as an attachment to existing processors with a minimum of modification of such processors, or as a built-in component of new processors during their manufacture, and which has flexibility in that it is adaptable for use in controlling other processor-related functions.